更新0110平衡二叉树Python3迭代法精简版代码

Author: Yufan SHENG

problems/0110.平衡二叉树.md

@@ -609,10 +609,13 @@ class Solution:
         while stack:
             node = stack.pop()
             if node:
-                stack.append(node)
+                stack.append(node)              # 中
                 stack.append(None)
-                if node.left: stack.append(node.left)
-                if node.right: stack.append(node.right)
+                # 采用数组进行迭代，先将右子树加入，保证左节点能够先出栈
+                if node.right:                  # 右
+                    stack.append(node.right)
+                if node.left:                   # 左
+                    stack.append(node.left)
             else:
                 real_node = stack.pop()
                 left, right = height_map.get(real_node.left, 0), height_map.get(real_node.right, 0)